What is meant by "making a covenant with the Most Merciful" mentioned in the Quran, and can one guarantee the acceptance of their supplications by making a covenant with Allah, and how is that done?

Verses 77-87 of Surah Maryam summarize that the disbeliever who claims to attain good in the Afterlife has no knowledge of the Unseen, nor a covenant from the Most Merciful; rather, he is exposed to torment. In contrast, the believers who have made a covenant with the Most Merciful through faith, monotheism, and righteous deeds will have security, salvation, and intercession on the Day of Judgment. The "covenant" is the pact that is preserved and observed, encompassing faith and righteous deeds. This is what establishes the believers' right to the bliss of the Afterlife, while disbelievers will be gathered to Hell alone, without wealth or offspring, because they did not make a covenant with Allah.